Power controller for mobile communication system wherein a signal to interference threshold is dynamically moved based on an error rate measurement

Abstract

An error rate of received signal is measured by a received signal error measuring unit 32, and a target SIR is changed by a target SIR decision unit using the error rate. It is also possible to detect error rate of received signal in an unit of frame using a CRC signal of a frame. It is further possible to detect error rate of received signal by detecting errors of known pilot signals inserted in a constant interval.

What is claimed is:  
     
       1. A transmission power controller of at least one of a base station and a mobile station in a mobile communication system including said base station and said mobile station, comprising: 
       means for measuring a received SIR (signal-to-interference plus noise power ratio);  
       means for comparing a measurement result of said received SIR with a target value of SIR;  
       means for outputting transmission power control information to an opposing station according to a result of said comparing of said measurement result of said received SIR with said target value of SIR;  
       means for receiving and demodulating said transmission power control information;  
       means for controlling transmission power of said opposing station according to said demodulated transmission power control information;  
       means for detecting a CRC (cyclic redundancy check) bit added to a wireless frame signal, and outputting a frame error detection signal when a CRC bit is not detected;  
       means for counting the number of said frame errors in a measuring time which is longer than a SIR measuring period, using said outputted detection signal;  
       means for comparing said number of counted frame errors with a predetermined frame error number setting value; and  
       means for changing said SIR target value according to a result of said comparing of said number of measured frame errors with said predetermined frame error number setting value, by either the base station or the mobile station.  
     
     
       2. A transmission power controller of at least one of a base station and a mobile station in a mobile communication system including said base station and said mobile station, comprising: 
       means for measuring a received SIR (signal-to-interference plus noise power ratio);  
       means for comparing a measurement result of said received SIR with a target value of SIR;  
       means for outputting transmission power control information to an opposing station according to a result of said comparing of said measurement result of said received SIR with said target value of SIR;  
       means for receiving and demodulating said transmission power control information;  
       means for controlling transmission power of said opposing station according to said demodulated transmission power control information;  
       means for detecting a CRC (cyclic redundancy check) bit added to a wireless frame signal, and outputting a frame error detection signal when a CRC bit is not detected;  
       means for counting the number of said frame errors in a measuring time which is longer than SIR measuring period, using said outputted detection signal;  
       means for determining a moving average of errors in an optional number of frames using said counted frame errors;  
       means for comparing said moving average of said measured errors with a predetermined setting value of frame errors; and  
       means for changing said SIR target value according to a result of said comparing of said moving average of said measured errors with said predetermined setting value of frame errors, by either the base station or the mobile station.  
     
     
       3. The transmission power controller as claimed in  claim 1  or  2 , wherein said means for changing said received SIR target value further comprises: 
       means for making an instruction to decrease said SIR target value by a predetermined step width when a number of measured frame errors or a moving average thereof is smaller than a setting value; and  
       means for making an instruction to increase said SIR target value by a predetermined step width when said number of frame errors or said moving average thereof is greater than a setting value.  
     
     
       4. A transmission power controller of at least one of a base station and a mobile station in a mobile communication system including said base station and said mobile station, comprising: 
       means for measuring a received SIR (signal-to-interference plus noise power ratio);  
       means for comparing a measurement result of said received SIR with a target value of SIR;  
       means for outputting transmission power control information to an opposing station according to a result of said comparing of said measurement result of said received SIR with said target value of SIR;  
       means for receiving and demodulating said transmission power control information;  
       means for controlling transmission power of said opposing station according to said demodulated transmission power control information;  
       means for detecting bit errors of known pilot signals inserted at a predetermined interval in a wireless frame, and outputting bit error detection information when the detected signal is different from the known signal;  
       means for counting said number of bit errors in a measuring time which is longer than SIR measuring period, using said outputted bit error detection information;  
       means for comparing said counted number of bit errors with a predetermined bit error number setting value; and  
       means for changing said SIR target value according to a result of said comparing of said measured number of bit errors with said predetermined bit error number setting value, by either the base station or the mobile station.  
     
     
       5. A transmission power controller of at least one of a base station and a mobile station in a mobile communication system including said base station and said mobile station comprising: 
       means for measuring a received SIR (signal-to-interference plus noise power ratio);  
       means for comparing a measurement result of said received SIR with a target value of SIR;  
       means for outputting transmission power control information to an opposing station according to a result of said comparing of said measurement result of said received SIR with said target value of SIR;  
       means for receiving and demodulating said transmission power control information;  
       means for controlling transmission power of said opposing station according to said demodulated transmission power control information;  
       means for detecting bit errors of pilot signals inserted at a predetermined interval in a wireless frame signal, and outputting bit error detection information when the detected signal is different from the known signal;  
       means for determining a moving average of bit errors in an optional period, using said outputted bit error detection information;  
       means for comparing said moving average of bit errors with a predetermined setting value of bit errors; and  
       means for changing said SIR target value according to a result of said comparing of said moving average of said measured errors with said predetermined setting value of bit errors, by either the base station or the mobile station.  
     
     
       6. The transmission power controller as claimed in  claim 4  or  5 , wherein said means for changing said received SIR target value further comprises: 
       means for making an instruction to decrease said SIR target value by a predetermined step width when a number of bit errors in measured pilot signals or a moving average thereof is smaller than a setting value; and  
       means for making an instruction to increase said SIR target value by a predetermined step width when said number of bit errors or said moving average thereof is greater than a setting value.  
     
     
       7. The transmission power controller as claimed in  claim 2 , wherein said means for determining the moving average of errors calculates 
       
         
           FER(n)=α×FER(n−1)+(1−α)×ERR  
         
       
       wherein FER is a frame error rate, n is a frame number, α is a forgetting factor, and ERR is a value indicating a pilot signal error detection result. 
     
     
       8. The transmission power controller as claimed in any one of  claim 1 ,  2 , and  7 , wherein said means for changing said SIR target value further comprises: 
       means for making an instruction to decrease said SIR target value by a predetermined step width when a number of measured frame errors or a moving average thereof is smaller than a setting value; and  
       means for making an instruction to increase said SIR target value by a predetermined step width when said number of frame errors or said moving average thereof is greater than a setting value.  
     
     
       9. The transmission power controller as claimed in  claim 5 , wherein said means for determining the moving average of errors calculates 
       
         
           BER(n)=α×BER(n−1)+(1−α)×ERR  
         
       
       wherein BER is a bit error rate, n is a frame number, α is a forgetting factor, and ERR is a value indicating a pilot signal error detection result. 
     
     
       10. The transmission power controller as claimed in any one of  claim 4 ,  5 , and  9 , wherein said means for changing said SIR target value further comprises: 
       means for making an instruction to decrease said SIR target value by a predetermined step width when a number of bit errors in measured pilot signals or a moving average thereof is smaller than a setting value; and  
       means for making an instruction to increase said SIR target value by a predetermined step width when said number of bit errors or said moving average thereof is greater than a setting value.